The present invention concerns a cream for protection of the scalp before the action of alkaline hair straightening agents, as well as a method of straightening hair using this protective cream.
For the lasting straightening of human hair, strongly alkaline adjusted hair straightening agents have acquired a great significance. Most of these agents contain as alkalization agent and simultaneously effective straightening component, alkali hydroxide, particularly 2 up to 10% by weight sodium hydroxide. Through the use of this agent a relatively fast straightening without noteworthy negative alterations of the hair structure is possible.
For performance of a hair straightening, the hair straightening agent, which as a rule is provided in cream form or gel form, is uniformly distributed onto the hair. The increased viscosity of the hair straightening agent should avoid a running off from the hair and, on the other hand, with subsequent combing, resist the tendency of the hair to return to its original curled form. After the frequent combing necessary for smoothing of the hair during the processing time, which amounts to about 5 up to 20 minutes, the hair is carefully rinsed with water, in order to remove the hair straightening agent.
Although the hairdresser protects his hands by means of gloves, with the described hair straightening method, even with the greatest care, a contact of the alkaline straightening agent with the scalp of the customer cannot be completely avoided. Strongly alkaline straightening agents, in particular those based upon alkali hydroxides, cause skin irritations on the scalp as well as the appearance of burns, and with longer working-in periods they can even lead to etching of the scalp.
It is known, in order to avoid a contact of the hair straightening agent with the scalp, to apply a protective cream of Vaseline.RTM. (a registered trademark representing petroleum jelly and being a mixture comprising hydrocarbon oils and paraffins with a melting range of 35.degree.-45.degree. C.) or water-containing gels, as well as oil-in-water- or water-in-oil-emulsions, thickly onto the hairy scalp as well as onto the forehead and the neck. During the working-in of the straightening agent on the hair it is, however, not possible to ascertain with these protective creams whether or not determined places on the scalp have nevertheless in risky manner come into contact with the hair straightening agents.
In other respects, protective creams composed of Vaseline.RTM. have the disadvantage that they are very difficult to remove again after the straightening operation.
Aqueous emulsions or gels have no sufficient protective activity, since the alkali lye is able to penetrate these after a short time.